The researchers were able to show that in this way two defect sites were formed on opposite poles of the particles, on which no molecules could be fixed. According to Stellacci, this is a necessary consequence of the topology of a tightly packed arrangement of long molecular chains on a spherical surface.
The coated gold particles thus somewhat resembled chemical molecules with exactly two binding sites each. In fact, the researchers actually succeeded in combining the gold particles into chains by means of short bridge molecules in a further chemical reaction: the connecting pieces could fit precisely into the defects at the poles of the particles.
According to Stellacci, chain formation corresponds to the polymerization reaction in the formation of plastics from individual monomer molecules. The longest of the gold chains produced by the researchers contained about 50, 000 individual beads. Scientists now want to increase the length of these chains, called "nanoplastics", by several orders of magnitude and then incorporate them into materials such as glasses. The aim is to set in this way their mechanical, electrical and optical properties as desired. displayGretchen DeVries (MIT) et al .: Science, Vol. 315, p. 348 Stefan Maier